Ability to limit scope of rust-analyzer check-on-save feature

[pacak]

Problem:

In a big cargo workspace working on anything imported by a bunch of other stiff is unnecessary painful - checking on saving (ni vim) take a long of time (during which I can't run tests because of a lock on the build directory) and I don't really care how other crates are affected until I decide to start working on them.

Desired solution

Automagically substitute --package <current> in cargo check / cargo clippy options when rust-analyzer calls them on save - current should correspond to a package current file belongs to.

[jhgg]

This looks (roughly) same as #12882

[Veykril]

Duplicate of #12882